(define (square x) (* x x))

(define (even? x) (= (remainder x 2) 0))

(define (smallest-divisor n)
   (find-divisor n 2))
 (define (find-divisor n test-divisor)
   (cond ((> (square test-divisor) n) n)
         ((divides? test-divisor n) test-divisor)
         (else (find-divisor n (+ test-divisor 1)))))
 (define (divides? a b)
   (= (remainder b a) 0))

(define (prime? n)
   (= n (smallest-divisor n)))



